Expert urges action to eradicate yaws, tropical disease
Half a century ago, a concentrated global effort nearly wiped a disfiguring tropical disease from the face of the earth. Now, says Case Western Reserve's James W. Kazura, MD, it's time to complete the work.
In a perspective column in the Feb.19 New England Journal of Medicine, Kazura responded to a research article that demonstrated positive results from a single oral dose of azithromycin to 83.8 percent (13,302) of 16,092 residents of Lihir Island, Papua New Guinea.
"We have the medical knowledge to achieve global eradication, and new evidence establishes proof of principle that single-dose azithromycin is the right approach in attempting to eliminate yaws by 2020," said Kazura, professor of International Health and Medicine, and Director, Center for Global Health & Diseases, Case Western Reserve University School of Medicine. "But do we have the infrastructure and the financial and human resources to make it happen?"
From 1954 to 1962, the World Health Organization (WHO) and UNICEF partnered on a massive eradication effort that involved 46 countries and hundreds of millions of examinations. The campaign ultimately lowered prevalence by 95 percent, to 2.5 million. Unfortunately, a range of factors stopped the ongoing progress, and by the 1970s, the disease again began to spread. WHO has set a new goal for eradication of 2020.
The results from Papua, New Guinea, give reason for hope. As an international team, including 16 authors reporting in the journal, the broad administration of the single-dose of azithromycin reduced prevalence of yaws from 2.4 percent to 0.3 percent within six months; at a year, the 0.3 percent figure remained unchanged.
Yaws is transmitted through direct contact with fluid from a skin ulcer of an infected individual into a skin abrasion or cut of an uninfected person. Because of the direct contact nature of the infection, yaws commonly occurs among children and family members. It also occurs in regions of the world with poor hygiene and lack of clean water for washing. That said, it is considered one of the infectious diseases with a realistic chance of eradication because it is only transmitted among humans.
Building off the findings from New Guinea, Kazura cited four key steps toward the goal of global eradication.
First, total community treatment requires ongoing, high-quality monitoring for both active and latent yaws. Such follow-up surveillance requires a minimum three-year commitment to track and control yaws infection in the community.
Second, the health care systems in affected areas must be minimally adequate to obtain and then administer the single dose of azithromycin to each infected patient. In highly remote regions of the world, a minimally adequate health care infrastructure is often absent. Additionally, health care systems are strained by dealing with other infectious diseases such as malaria, worm parasites and possibly Ebola.
"If we are to succeed in eradicating yaws infection, azithromycin will have to be put in a package that can be handled in those places of the world where infrastructure is very weak," Kazura said. "This is a disease that occurs among the poorest of the poor in the world."
Third, he advocates more effective mapping systems to identify zones of high yaws incidence, and then moving surveillance and treatment resources to those regions. Yaws tends to be highly centralized in specific geographic locations rather than scattered through entire continents. Currently, the highest incidence of yaws distribution is in central Africa and the Southeast Asia island chains of Indonesia, Papua New Guinea and Solomon Islands.
Finally, eradicating yaws infection will require continued commitment from susceptible communities in terms of monitoring and treating the infection. The Papua New Guinea research by Mitja and colleagues did set the bar for yaws-affected communities throughout the world—azithromycin administration to 80 percent or more of eligible residents in the community. The effectiveness of total community treatment with one-dose azithromycin gives WHO the evidence it needs to obtain funding from government and non-government sources to apply available, inexpensive and safe tools to eradicate yaws infection.
"If total community treatment is done properly, yaws infection is gone forever," Kazura said. "Compared to malaria and worm infections, yaws eradication should be more approachable and much easier to achieve. Yaws is in line for that major step forward in advancing human health at the world level."